1. Field of the Invention
The present invention relates to a color filter, and particularly to a color filter suitable for use in resolution of fine color in color image pick-up devices, color sensors, color displays and so forth. The present invention also relates to a liquid crystal device for color display, comprising a color filter built in the liquid crystal device.
2. Related Background Art
As liquid crystal devices for color display, there have been conventionally used color filters produced by vapor-deposition of a subliming dye on electrodes as disclosed in U.S. Pat. No. 4,470,667 (Y. Okubo et al.). However, the subliming dye used in Y. Okubo et al. had a problem that the color selectivity is so small and a color filter having a desired tone cannot easily be produced. Accordingly, the color display thus formed has been insufficient in color reproducibility.
U.S. Pat. No. 4,367,924 (N. A. Clark et al.), U.S. Pat. No. 4,563,059 (N. A. Clark et al.) and U.S. Pat. No. 4,639,089 (S. Okada et al.) incidentally disclose ferroelectric chiral smectic C or H liquid crystal devices exhibiting a quick response and having memory effect.
It has been attempted to apply this ferroelectric liquid crystal device to a color display by using color filters built in the crystal device. In this ferroelectric liquid crystal device, however, the distance between a pair of substrates must be controlled to be 1 .mu.m to 2 .mu.m, which is about 1/10 to 1/5 of conventional TN liquid crystal devices, and this distance must be controlled uniformly over the entire cell. (Assuming the precision of the distance between substrates as 10% or less, and assuming the distance between substrates as 1 .mu.m, the precision is in the range of .+-.0.1 .mu.m.)
Accordingly, in the above ferroelectric liquid crystal device, spacers such as glass beads or silica beads are used in a larger amount than in the conventional TN liquid crystal devices. This has caused a problem that the color filter in the ferroelectric liquid crystal cell can be damaged by the beady spacers.
On the other hand, known color filters include those disclosed in Japanese Laid-open Patent Publications No. 46325/1983, No. 78401/1985, No. 184202/1985, No. 184203/1985, No. 184204/1985, No. 184205/1985, No. 134807/1980, No. 16407/1982, No. 16408/1982, No. 74707/1982, No. 129707/1985, etc. The problems mentioned above could not be solved even by use of these color filters.